The prior art is replete with apparatus for testing the effect of sunlight on textiles and other materials. By and large, most of the patentees utilize an artificial source of light to simulate sunlight. As disclosed in U.S. Pat. No. 3,433,944 issued Mar. 18, 1969, to Andrew Truhan for a "Radiant Energy Stability Test Chamber Having Air Circulating Means", the radiant energy producing means usually comprises, but is not limited to, fluorescent light, incandescent light, ultraviolet light, and combinations thereof.
It has been found, however, that it is not possible to accurately extrapole from the test results achieved under artificial light the degradation that will occur in textiles and other materials under actual conditions such as when the fabrics are used in the passenger compartment of an automobile body. It was apparent, however, there was a need for a controlled, high temperature test for vehicle body cloths and other materials for automotive interior applications. This test was not to be done with any laboratory apparatus equipped with an artificial light source. The materials had to be exposed to natural sunlight under glass in an enclosure approximating the passenger compartment of a standard size automobile.
After several years of discussion between representatives of the assignee of the present application and personnel of a firm having expertise in natural sunlight testing, certain criteria were established. The test chamber would have to be a black box having an insulated bottom, side and end walls and a closure for the top consisting of a hinged panel of standard automobile glass. A sample rack would have to be located beneath the glass and thermostatically controlled heater strips in the bottom of the box beneath the sample racks. Suspended between the heater strips and the sample rack would be a heat sink, preferably an aluminum sheet. Also, an air mixing system to level temperature distribution would be needed to some extent compensate for the wind chill factor and variations in cloud cover.
An object of this invention is to provide a test chamber that would meet the desired criteria and yet would have a simplified construction and arrangement that would provide the necessary conditions for the evaluation of the test samples.